commit b2cb9339f7d963d2b16b8dcf3af5313f996e4eb5
author William A. Kennington III <wak@google.com> Thu Oct 04 16:01:53 2018 -0700
committer William A. Kennington III <wak@google.com> Fri Oct 05 15:02:59 2018 -0700
tree e57aba51e75dd3872cea0808e4ccdca07ea3fb00
parent 20adbc2d459123772ecd2d17009e1db0dd6314f2

mapbox/variant: Align API with std::variant

Tested:
    Builds and unit tests still pass. Manually tested that
    has_alternative works as expected.

Change-Id: Iae8309c09a6aac6b9b12164d5fe7ae4e484cb905
Signed-off-by: William A. Kennington III <wak@google.com>

mapbox/variant.hpp

diff --git a/mapbox/variant.hpp b/mapbox/variant.hpp
index 14fe75c..9f039bc 100644
--- a/mapbox/variant.hpp
+++ b/mapbox/variant.hpp
@@ -1079,6 +1079,16 @@
     return V::binary_visit(v0, v1, std::forward<F>(f));
 }
 
+// is interface
+
+#ifdef HAS_EXCEPTIONS
+template <typename ResultType, typename T>
+auto holds_alternative(T const& var) -> decltype(var.template is<ResultType>())
+{
+    return var.template is<ResultType>();
+}
+#endif
+
 // getter interface
 
 #ifdef HAS_EXCEPTIONS